Internal combustion engines, particularly air-cooled internal combustion engines, often include both a flywheel and a fan that are coaxially-aligned with, and rotated by, the crankshaft of the engine. In some such engines, the flywheel is attached to the crankshaft and the fan in turn is attached to the flywheel, such that rotation of the crankshaft ultimately causes rotation of both the flywheel and the fan.
Various techniques are currently employed to attach a fan to a flywheel in such engines. In some current arrangements, the fans are made of plastic and molded so as to include “lugs” or protrusions (also made of plastic) that fit into complementary holes on the flywheel. These lugs are intended to guarantee that the fan rotates along with the flywheel, that is, to maintain rotational retention between the fan and the flywheel. Although suitable for some applications, such arrangements involving lugs are limited in their usefulness because, due to the stress of operation, the lugs can break over time. This is particularly the case because the lugs are often only relatively loosely fitted into the complementary holes, such that there is some ability for the lugs to shift within the holes.
Given these limitations, such configurations involving lugs and complementary holes particularly are not well suited for some applications in which there is a need or desire for a long-lasting, high durability connection. Yet other conventional techniques for attaching a fan to a flywheel have other disadvantages. For example, one additional technique is simply to employ four screws to attach the fan to the flywheel, by screwing the screws through holes in the fan and then subsequently into complementary tapped holes in the flywheel. Although this technique results in a long-lasting, high durability connection between the fan and the flywheel, this technique is (by comparison with the aforementioned use of lugs and complementary holes) expensive and tedious to perform from a manufacturing standpoint.
For at least these reasons, therefore, it would be advantageous if a new and/or improved technique, method, and/or apparatus could be developed for attaching a fan and flywheel together in an internal combustion engine, particularly so that the fan and flywheel experienced the same rotation. It would additionally be advantageous if, for example, such a new and/or improved technique, method, and/or apparatus achieved a more long-lasting, durable attachment of the fan and flywheel to one another than has been achieved by conventional arrangements involving lugs and complementary holes, and/or allowed or facilitated the attachment of the fan and flywheel in a manner that was less expensive and/or less difficult to perform than attachment involving screws and tapped holes as discussed above.